1. Field of the Invention
This invention relates to a semiconductor chip and semiconductor device manufacturing method which facilitates defect inspection, and a wafer for obtaining such a semiconductor chip.
2. Description of the Related Art
In order to achieve lower costs for semiconductor chips, it is important that the number of semiconductor chips obtained from a single wafer be increased. As shown in FIG. 10, wafers generally comprise a plurality of semiconductor chips 3 arranged in a matrix, and scribe lines 9 of a prescribed width provided between the individual semiconductor chips 3. A dicing system or similar is used to cut the wafer 1 along the scribe lines 9, to divide the wafer into individual semiconductor chips 3.
A TEG (Test Element Group) comprising check transistors is formed on the wafer 1; this TEG is used to judge the quality of semiconductor chips 3 at the wafer stage. However, if a TEG is formed within a semiconductor chip 3, the area of the semiconductor chip 3 is increased, and so normally TEGs are formed on the above-described scribe lines 9. Also, alignment marks are necessary for mask positioning in order to manufacture semiconductor chips 3; such alignment marks are also formed on the above scribe lines 9. Consequently the scribe lines 9 must be made sufficiently wide to enable placement of both TEGs and alignment marks, and so there is a problem that as the widths of scribe lines 9 are increased, the number of semiconductor chips 3 which can be formed in a single wafer 1 is decreased.
Hence there have been various proposals to obtain as many semiconductor chips 3 as possible from a single wafer 1. For example, in Japanese Unexamined Patent Application Publication No. 2003-258049, pages 3 to 5, FIG. 2, Nakahara et al., a method of changing the width of scribe lines in the vertical direction and horizontal direction is disclosed. According to Nakahara et al., because in LCD drivers the electrodes corresponding to a row of pixels in the horizontal direction or in the vertical direction of an LCD are arranged in a row in the vertical direction or in the horizontal direction, semiconductor chips have long and narrow rectangular shapes, and consequently if scribe line widths are made the same in the width direction and in the length direction of the semiconductor chips, the area fraction occupied by scribe lines in the width direction increases, so that the area of the wafer that is wasted is increased; in order to resolve this problem, a first dividing extending region in the width direction is made wider than a second dividing region extending in the length direction, and consequently the number of semiconductor chips obtained is increased.
It has now been discovered that by using the above method, compared with a method of making scribe lines wider in both the vertical direction and the horizontal direction, the number of semiconductor chips obtained from a single wafer can be increased; but when the shape of semiconductor chips is nearly square, the area occupied by scribe lines in one direction (the above-described first dividing area) is increased, and the number of semiconductor chips obtained cannot be increased so much.
In structures of the above related art, the widths of scribe lines adjacent to the upper, lower, left and right edges of each semiconductor chip are either equal, or the scribe lines adjacent to each of the upper and lower edges or to the left and right edges are of equal width, so that the external view of each semiconductor chip is the same, and it is not possible to determine to which portion of a mask pattern a prescribed semiconductor chip corresponds, or in what position of the wafer the semiconductor chip has been placed; and there is the problem that when a defect is detected in inspections, semiconductor chip placement information cannot be used to check for mask pattern faults, nor can other defect analysis be performed rapidly.